Pregabalin prescriptions in the United Kingdom: a drug utilisation study of The Health Improvement Network (THIN) primary care database

AIM

In Europe, pregabalin is approved for treatment of neuropathic pain, general anxiety disorder (GAD) and as adjunctive therapy for epilepsy. The purpose of this study was to assess utilisation of pregabalin in the UK, including patients with a recorded history of substance abuse, from a large general practice database.

METHODS

This observational drug utilisation study (DUS) analysed pregabalin prescription data from the UK Health Improvement Network primary care database between September 2004 and July 2009. Patient demographics, diagnoses (by READ codes) and pregabalin dosing data were collected. Diagnosis codes were used as proxy for approved indication for pregabalin.

RESULT

A cohort of 18,951 patients was prescribed pregabalin; dosing information was available for 13,480 (71.1%). Median age of patients was 58 years, and majority were female (60.1%). Median (interquartile range) prescribed average daily dose (ADD) of pregabalin for all patients was 150.0 (162.5) mg/day; this was highest in patients with epilepsy (191.9 mg/day), followed by neuropathic pain (158.0 mg/day) and GAD (150.0 mg/day). Only 1.0% (136/13,480) of patients were prescribed an ADD of pregabalin over the maximum approved dose of 600 mg/day. Of these, 18.4% (25/136) of patients had a history of substance abuse compared with 14.0% (1884/13,480) in the full population.

CONCLUSION

Data from this DUS indicated that the majority of pregabalin prescribing in the UK was consistent with product labelling. The proportion of patients with prescribed ADD > 600 mg/day was small and with a similar proportion with a history of substance abuse as in the full population.

Comparison of discriminatory power and accuracy of three lung cancer risk models

Background:

Three lung cancer (LC) models have recently been constructed to predict an individual's absolute risk of LC within a defined period. Given their potential application in prevention strategies, a comparison of their accuracy in an independent population is important.

Methods:

We used data for 3197 patients with LC and 1703 cancer-free controls recruited to an ongoing case–control study at the Harvard School of Public Health and Massachusetts General Hospital. We estimated the 5-year LC risk for each risk model and compared the discriminatory power, accuracy, and clinical utility of these models.

Results:

Overall, the Liverpool Lung Project (LLP) and Spitz models had comparable discriminatory power (0.69), whereas the Bach model had significantly lower power (0.66; P=0.02). Positive predictive values were highest with the Spitz models, whereas negative predictive values were highest with the LLP model. The Spitz and Bach models had lower sensitivity but better specificity than did the LLP model.

Conclusion:

We observed modest differences in discriminatory power among the three LC risk models, but discriminatory powers were moderate at best, highlighting the difficulty in developing effective risk models.

Epidermal growth factor (EGF) gene polymorphism, gastroesophageal reflux disease (GERD), and esophageal adenocarcinoma (EAC) risk

11029

Background: Single nucleotide polymorphisms (SNPs) of key cancer genes, such as EGF A61G, are associated with an elevated risk of EAC, but the lack of full penetrance indicates that the effects of these SNPs on esophageal carcinogenesis are modified by additional genetic or environmental variables. Since GERD is an established risk factor for EAC, we evaluated whether the association between EGF polymorphism and EAC development is altered by the presence of GERD. Methods: EGF genotyping of DNA samples was performed and GERD history was collected for 309 EAC patients and 275 matched healthy controls. Associations between genotypes and EAC risk were examined with adjusted logistic regression. Genotype-GERD relationships were explored using analyses stratified by GERD history and joint effects models that considered severity and duration of GERD symptoms. Results: Baseline characteristics were comparable between cases and controls except that EGF variants (A/G or G/G) were more common (p=0.02) and GERD was more prevalent (p<0.001) in cases than in controls. When compared to the EGF wild type A/A genotype, the G/G variant was associated with an increased risk of EAC (OR 1.9; 95% CI, 1.2–3.0; p=0.007). Stratified analyses revealed that the G/G variant contributed to a substantial increase in EAC risk among individuals with GERD, but a slight decrease in risk for GERD-free individuals (see table). In the joint effects models, the odds of EAC was also highest for G/G patients who either experienced frequent GERD of more than once per week (OR 21.8; 95% CI, 5.1–94.0; p<0.001) or suffered GERD for longer than 15 years (OR 22.4; 95% CI, 6.5–77.6; p<0.001). There was a highly significant interaction between the G/G genotype and the presence of GERD (p<0.001). Conclusions: EGF A61G polymorphism exerts its effect on EAC susceptibility through an interaction with GERD. Performing EGF genotyping for patients with severe or longstanding GERD can help to identify individuals at the greatest risk of EAC. [Table: see text]

No significant financial relationships to disclose.

Stage and histology influence the relationship between MDM2 promoter polymorphism and esophageal cancer and overall survival (OS)

21047

Background: A single nucleotide polymorphism in the MDM2 promoter (SNP309) has been found to affect OS of advanced stage gastric adenocarcinoma (AD) and early stage squamous (SQ) cell carcinoma of the lung. The aim of this study was to evaluate the role of this polymorphism in the prognosis of esophageal cancer, another aerodigestive cancer. Methods: 150 early stage (E) and 118 locally advanced stage (LA) esophageal cancers were genotyped for MDM2 SNP309 using Taqman. The primary endpoint was overall survival (OS). Results: E disease: n=23 stage I; n=127 stage II. LA disease: n=93, Stage III; n=25, Stage IVA. AD comprised 215 (81%), while SQ comprised 45 (17%) of cases; 8 (3%) had poorly differentiated tumors. Median follow-up = 32 months. Median OS were 36 and 21 months for E and LA disease, respectively. Both histology and disease stage affected the relationship between SNP309 and esophageal cancer OS (see Table ). The wildtype T/T genotype conferred a worse OS in E patients (log-rank, p=0.03), especially those with AD (log-rank, p=0.003). In Cox proportional hazards interaction analyses, after adjusting for age, gender, stage and PS, there were statistically significant interactions between MDM2 SNP309 and disease stage (interaction p=0.004) and between MDM2 SNP309 and histologic subtype (AD vs. SQ)(interaction p=0.02). Thus, the direction of SNP309 association from our AD and E esophageal cancer patients are opposite to those of our SQ and LA esophageal cancer patients. However, our SQ and LA results are similar to the SQ lung cancer and advanced stage gastric cancers previously reported. This suggests that biologic mechanisms underpinning the prognostic role of SNP309 are dependent on extent of disease and histologic subtype. Conclusion: Histology and disease stage interact with the prognostic role of MDM2 SNP309 polymorphism in esophageal cancer OS.

[Table: see text]

No significant financial relationships to disclose.

MMP1 1G/2G promoter polymorphism and risk of esophageal adenocarcinoma

10555

Background: The 2G allele of the MMP1 -1607 1G/2G promoter polymorphism creates an Ets binding site that leads to increased transcriptional and enzyme activity, particularly in the presence of growth factors and cytokines. This polymorphism has been associated with greater risk of cancer (e.g., renal cell, lung and oral cancers, glioblastomas) and cancer invasiveness (e.g., melanoma, cervical, lung and colorectal cancer). The aim of the current study was to evaluate the role of this MMP 1G/2G polymorphism in the risk of esophageal adenocarcinoma (EA). Methods: We evaluated 323 histologically confirmed EA cases and 464 healthy controls frequency-matched for age and gender. Genotyping of the MMP1 1G/2G promoter polymorphism involved a Taqman approach. All EAs had endoscopic evidence showing that the center of the tumors were located at or above the gastroesophageal junction. Odds Ratios (OR) were calculated using multivariate logistic regression, adjusted for age, gender, smoking status, and body-mass index (BMI) at the age of 18 years (to represent a healthy adult BMI). Results: Genotype frequencies were: 33% (1G/1G), 47% (1G/2G) & 20% (2G/2G) in controls; in cases, 26% (1G/1G), 50% (1G/2G) & 24% (2G/2G). 88% of cases were male. The MMP1 2G/2G and 1G/2G genotypes conferred a greater risk of EA, with adjusted ORs of 1.50 (95%CI=1.0–2.3) and 1.34 (95%CI=0.9–1.9), respectively, when compared with the wildtype 1G/1G genotype. The 2G allele (2G/2G + 1G/2G) conferred an adjusted OR of 1.38 (95%CI=1.0–1.9). By stage, the adjusted ORs for the 2G allele were 1.26 (95%CI=0.8–2.1), 1.45 (95%CI=0.9–2.3), & 1.54 (95%CI=0.9–2.7) for node negative, node-positive, and metastatic disease, respectively. Conclusions: The 2G allele of the MMP1 -1607 1G/2G polymorphism was associated with an increased risk of EA in this analysis. In addition, there was a non-significant trend towards conferring greater risk in the more advanced stages of EA, suggesting a possible role of this polymorphism in the invasiveness of this cancer.

No significant financial relationships to disclose.

Epidermal growth factor receptor polymorphisms and clinical outcomes in non-small-cell lung cancer patients treated with gefitinib

The-216G/T, -191C/A, intron 1 and Arg497Lys epidermal growth factor receptor (EGFR) polymorphisms were evaluated in 92 advanced non-small-cell lung cancer patients treated with gefitinib, an EGFR tyrosine-kinase inhibitor. Improved progression free survival (PFS) was found in patients homozygous for the shorter lengths of intron 1 polymorphism (S/S; S=16 or fewer CA repeats; log-rank test (LRT) P=0.03) and for patients carrying any T allele of the -216G/T polymorphism (LRT, P=0.005). When considered together, patients with intron 1 S/S genotype and at least one T allele of -216G/T had improved PFS (LRT P=0.0006; adjusted hazard ratio (AHR), 0.60 (95% confidence interval, 0.36-0.98)) and overall survival (LRT P=0.02; AHR, 0.60 (0.36-1.00)) when compared with all others. The T allele of -216G/T was also associated with significantly higher rates of stable disease/partial response (P=0.01) and a significantly higher risk of treatment-related rash/diarrhea (P=0.004, multivariate model). EGFR intron 1 and -216G/T polymorphisms influence clinical outcomes in gefitinib-treated non-small-cell lung cancer patients.